lineset installed below concrete & motorized dampers

Is there any way a lineset can be installed under concrete? i've been told both yes and no and don't know who to believe. we are building on a hillside and the lower level floor is 3 to 4 feet above grade. we live in northern ohio (if that makes any difference) and will probably use the air less than a dozen days a summer. my bryant/ hvac guy said that bryant will not allow it because of slugging problems (i contacted bryant and they didn't know and said to ask the dealer). is this true? if yes, what is the likelyhood of this happeneing? if this were to happen, what could be done to correct it? i was going to install a 4" pvc sleeve to run it thru. not sure of the best way to insulate it. any suggestions?

on another matter- do the round in-duct motorized dampers work very well. we will have several rooms that will not be used on a regular basis. talked about zoning the system, but at under a hundred bucks each, i thought this would be easier and more cost effective. what options would i have to control them? would a simple 115v lighting switch work? my heating guy said he has just started using them.

This is done quite frequently in situations like yours or when customers want to remote the cond units from the house because they are unsightly or because of noise. At a minimum we normally add a liquid line solenoid at a location close to the evap coil. When the compressor comes on the solenoid comes on. when the compressor is off the solenoid closes and stopping refrigerant flow and minimizing the migration of refrigerant and oil to the lowest and coldest spot which usually is underground. This works well on short runs. If it was a long run we would add an accumulator. As for the covering/protection we use the corrugated drainage tubing ( without the holes in it ). It is 4" and flexible and easy to work a lineset through. Insulate both lines and seal it as best as possible to prevent any water from laying in there

You do not want the vapor line to be shaped like a long deep 'p'-trap. If the velocity of the refrigerant a little slow, the compressor oil could pool in the line and not return to the compressor to prevent bearing failure.
Otherwise, the above accumilator/seliniod addition would be needed to reduce the chance a large slug of liquid returning to a compressor and liquids do not compress